Thai security officials are moving in on suspects behind the grenade attacks on anti-government protesters over the weekend as demonstrators besieged more government offices.

Yesterday, protesters surrounded a state bank and at least 12 provincial halls in southern Thailand in their latest attempt to force the caretaker government of Prime Minister Yingluck Shinawatra to resign and abandon a general election scheduled for February 2.

Protest leader Suthep Thaugsuban, a former senior member of the opposition Democrat Party which is boycotting the snap election, had told protesters to lay siege to state offices to stop civil servants from working.

Protesters did just that yesterday in provinces such as Nakhon Si Thammarat, Phuket and Surat Thani, which are all Democrat strongholds.

According to Thai daily Khaosod, one official in Surat Thani was even detained by protesters briefly for trying to work.

An arrest warrant, meanwhile, has been issued for a man believed to be involved in a grenade attack on Sunday which injured almost 30 people. The police also offered a 500,000 baht (US$15,239) reward for information on the man.

Since January 13, anti-government protesters have blockaded major intersections in Bangkok and vowed to stay on the streets until Yingluck resigns.

While their numbers appeared to have dwindled, attacks on protesters have become more frequent. A series of drive-by shootings and grenade attacks have led security officials to consider imposing a state of emergency.

Such a decree would possibly require the military to be involved. But so far, it has remained overtly neutral in the political crisis.

While it is not clear what motivated the attacks, protesters claim that it is the work of the government.

Suthep told supporters on Sunday night: "Yingluck has been sending her guard dogs to attack us."

The current crisis, which began in late October and is the latest instalment of an eight-year on-off battle between political forces aligned with and against self-exiled former premier Thaksin Shinawatra, has so far failed to dislodge Yingluck, his younger sister.

Her Puea Thai party, which scored a landslide win in the 2011 election, is just two weeks away from getting a fresh mandate.

The anti-government campaign is supported by many in the Bangkok elite, royalists as well as the urban middle class, who are calling for political reforms under a "people's council" before elections are held.

Puea Thai's supporters, who hail mainly from the rural northern and north-eastern regions of Thailand, have stayed their hand so far, but are expected to come out in droves should Yingluck be forced out through extra-constitutional measures like a military coup.

There are fears that the violence will escalate as protesters ramp up attempts to sabotage the upcoming election.